1. Field of the Invention
The present invention relates to a slide switch for use in various electronic devices such as portable telephones and digital cameras.
2. General Background
Nowdays, slide switches of the so-called auto return type are widely used in various electronic devices such as portable telephones and digital cameras. The slide switches of this type are usually operable for changing a sound volume level or a zooming level, for example, and they return to a neutral position when the operation stops. Such a conventional switch will be described below.
The conventional slide switch generally comprises an insulative housing, a plurality of stationary contacts fixed in the housing, a slide member moveable mounted onto the housing, and a cover covering the housing and the slide member.
The housing has a substantially longitudinal configuration with a top opening, and the housing comprises a bottom surface and a plurality of side surfaces around said bottom surfaces. Said bottom surface and side surfaces cooperatively define a cavity for accommodating the slide member. The stationary contacts are embedded in the bottom surface of the housing. The slide member comprises a containing portion recessed in the bottom surface substantially in the center thereof and an operating portion extending from the housing. A moveable contact is fixed to the slide member for connecting to or disconnecting from the stationary contacts. A coil spring is defined for attaching to the slide member.
In assembly, the moveable contact is fixed to the slide member and the coil spring attaches to the slide member. Then the slide element is mounted into the cavity of the housing from the top opening. The containing portion is received in the cavity and the operating portion extends out of the cavity from a cut out of the lateral side surface. At this time, the coil spring is slightly pre-compressed between the containing portion and corresponding side surface of the housing. The cover subsequently covers the housing and the slide member for preventing EMI.
In use, the slide switch is mounted onto a printed circuit board, and the stationary contacts connect with corresponding circuits of the printed circuit board. At this time, the moveable contact contacts with some predetermined stationary contacts. When the operating portion is actuated from the neutral position to the pressed position, the coil spring is compressed, and the moveable contact contacts with some other predetermined stationary contacts in the bottom surface. When the operating portion is released, the slide member will auto return to the neutral position under the pressure of the coil spring.
However, one problem with this conventional slide switch is that the coil spring is prone to be ejected from the predetermined position or even from the cavity of the housing when the slide element is sharply pressed by the released spring to return to the neutral position. Therefore, reliable mechanical performance of the slide switch can not be ensured.
In view of the above, a new slide switch which overcomes the above-mentioned disadvantages is desired.